The Square Kilometre Array (SKA) will operate in frequency ranges often used by military radar and other communications technology. It has been shown that if Extraterrestrial Intelligences (ETIs) communicate using similar technology, then the SKA should be able to detect such transmissions up to distances of∼100 pc (∼300light years) from Earth.  However, Mankind has greatly improved its communications technology over the last century, dramatically reducing signal leakage and making the Earth “radio quiet”. If ETIs follow the same pattern as the human race, will we be able to detect their signal leakage before they become radio quiet? We investigate this question using Monte Carlo Realisation techniques to simulate the growth and evolution of intelligent life in the Galaxy.  We show that if civilisations are “human” in nature (i.e. they are only “radio loud” for∼100years, and can only detect each other with an SKA-like instrument out to 100 pc, within a maximum communication time of 100 years), then the probability for such civilisations accidentally detecting each other is low (∼10−7), much lower than if other, dedicated communication techniques are permissible (e.g.  optical SETI or neutrino communication).

“I have always wondered where we come from. Even as a child I wanted to know where the elements come from: the calcium in my bones, the carbon in my muscles, the iron in my blood. I found out that these were first formed at the very beginning of the Universe, by the first generation of stars. With this discovery, remarkably, we are starting to actually see such objects for the first time.”